Grade 7 · Unit 1 · Lesson 3 · part 4 of 5
Comparing two relationships
The standard also asks you to compare two proportional relationships: decide which is more, and say why.
Comparing two relationships
The standard also asks you to compare two proportional relationships: decide which is more, and say why. Mia babysits and earns $45 for 5 hours. Jordan mows lawns, and his table shows 2 hours $16, 3 hours $24, 5 hours $40. Who earns more per hour?
| Hours | Pay |
|---|---|
| 5 | $45 |
| 45 ÷ 5 = $9 an hour | |
| Hours | Pay |
|---|---|
| 2 | $16 |
| 3 | $24 |
| 5 | $40 |
| 40 ÷ 5 = $8 an hour | |
Mia's unit rate is $9 an hour and Jordan's is $8 an hour. So for the same 10 hours, Mia earns 10 × 9 = $90 and Jordan earns 10 × 8 = $80. Mia's job pays more.
One warning. Comparing only makes sense when the units match. Dollars per hour against dollars per hour is a fair comparison. Dollars per hour against dollars per lawn is not, because an hour and a lawn are different things. Line up the units first, then compare the unit rates.